The present invention concerns centrifugal processing apparatus, and more particularly, apparatus employing umbilical tubing which is rotated with respect to a stationary base.
Centrifugal processing systems are used in many fields. In one important field of use, a liquid having a suspended mass therein is subjected to centrifugal forces to obtain separation of the suspended mass.
As a more specific example, although no limitation is intended herein, in recent years the long term storage of human blood has been accomplished by separating out the plasma component of the blood and freezing the remaining red blood cell component in a liquid medium, such as glycerol. Prior to use, the glycerolized red blood cells are thawed and pumped into the centrifugating wash chamber of a centrigual liquid processing apparatus. While the red blood cells are being held in place by centrifugation, they are washed with a saline solution which displaces the glycerol preservative. The resulting reconstituted blood is then removed from the wash chamber and packaged for use.
The aforementioned blood conditioning process, like other processes wherein a liquid is caused to flow through a suspended mass under centrifugation, necessitates the transfer of solution into and out of the rotating wash chamber while the chamber is in motion. Thus while glycerolized red blood cell and saline solution are passed into the wash chamber, waste and reconstituted blood solutions are passed from the chamber. To avoid contamination of these solutions, or exposure of persons involved in the processing operation to the solutions, the transfer operations are preferably carried out within a sealed flow system.
One type of centrifugal processing system which is well adapted for the aforementioned blood conditioning process uses the principles of operation described in Dale A. Adams U.S. Pat. No. 3,586,413. The apparatus of the Adams patent establishes fluid communication between a rotating chamber and stationary reservoirs through a flexible interconnecting umbilical cord without the use of rotating seals, which are expensive to manufacture and which add the possibility of contamination of the fluid being processed.
The primary embodiment of the Adams patent comprises a rotating platform which is supported above a stationary surface by means of a rotating support. A tube is connected to the stationary support along the axis of the rotating platform and the rotating support, with the tube extending through the rotating support and having one end fastened to the axis of the rotating platform. A motor drive is provided to drive both the rotating platform and the rotating support in the same relative direction at speeds in the ratio of 2:1, respectively. It has been found that by maintaining this speed ratio, the tube will be prevented from becoming twisted. An improvement with respect to this principle of operation, comprising a novel drive system for a centrifugal liquid processing system, is disclosed in Khoja, et al. U.S. Pat. No. 3,986,442. In the Khoja, et al. patent, a novel drive system is provided for driving a rotor assembly at a first speed and a rotor drive assembly at one-half the first speed, in order to prevent an umbilical tube from becoming twisted.
While the Adams patent broadly suggests driving the rotating support to allow the tube to provide the necessary torque for driving the rotating platform, such a tube drive is difficult to achieve because of torsional stresses that are experienced by the umbilical tube and because of the frictional contact of the tube, during rotation thereof, with the machine.
It is, therefore, an object of the present invention to provide centrifugal processing apparatus in which rubbing contact of the umbilical tube with the apparatus is alleviated or obviated, thus reducing or eliminating tubing wear.
Another object of the present invention is to provide centrifugal processing apparatus in which the tubing is connected so as to reduce the torsional stresses in the tubing.
Another object of the present invention is to provide centrifugal processing apparatus in which relatively high speeds may be achieved with the torsional stresses in the tubing being no greater than the torsional stresses in tubing of prior art centrifugal processing apparatus at lower speeds.
A further object of the present invention is to provide centrifugal processing apparatus in which a greater load can be rotated with the same or less torsional stresses than are present in prior art systems having smaller loads.
A still further object of the present invention is to provide centrifugal processing apparatus which allows the use of a broader range of tubing materials in a tube-drive system, by alleviating or obviating rubbing contact of the tubing with the apparatus.
Another object of the present invention is to provide a centrifugal processing apparatus which is constructed to reduce the amount of heat that is normally generated in prior art centrifugal processing apparatus.
A further object of the present invention is to provide a centrifugal processing apparatus which is simplified in construction and is efficient to manufacture.
Other objects and advantages of the present invention will become apparent as the description proceeds.